Lens mount



Feb. 10, 1931. K KRUENlNG 1,792,171

LENS MOUNT Filed Jan. 25, 1928 INVENTOR RNEY 5 f Patented Feb. 1o, 1931 UNrrEDJ s 'rA'rns PATEN'D OFFICE KARL XR'UENING, OF JAMAICA, NEW YORK,

ASSIGNOR T KOLLMORGEN OPTICAL COR- PORATION, 0F BROOKLYN, NEW YORK, A CORIEORATION 0F NEW YORK LENS MOUNT Application led January 25, 1928. Serial No. 249,223.

This invention relates to mounts for lenses and has particularreference to the mounting of projection lenses in the motion picture industry. Such a lens system is usually composed of four lenses, one pair being cemented together and termed the front element, while the two lenses of the other set are usually uncemented. The uncemented lenses forde-` scriptive purposes will be referred to as the m rear element. These lenses must be removed from their mountsl from time to time for cleaning purposes and as this is done usually by the operator of the projection machine, the lenses either through ignorance or carelessness, are often reversed or become inserted in the wrong position, resulting .in images of very poor quality. The present invention has for anobjeet the provision of a' construction wherein this possibility is overcome.

I have shown several embodiments of my invention as illustrating various ways of accomplishing my purpose.

In the accompanying drawings, Fig. 1 is a viewv inside elevation-partly in section of a lens system constructed in accordance with this invention;

Fig. 2 is a section on the line 2 2 of Fig. 1 Fig. 3 is a view similar to Fig. 1 of a modilied form of my invention; Fig. 4.is a fragmentary sectional view on -an enlarged scale of the rear element of the projecting apparatus of Fig. 3; and

A Fig. 5 is a further modification. y

Referring to the drawings in detail and first of all to Figs. 1 and 2,1 designates the lens tube of my improved mount. The front element of this projecting apparatus is composed of two lenses 2 and 3 which; as illustrated, are cemented together. Threaded into the forward end of the tube 1 is a retaining ring 4, provided with a reduced portion 5 threaded'externally as indicated at 6 and internally as indicated-atl The retaining ring 4 is provided adjacent its ,outer 'end with a shoulder 8 conveniently provided by reducing the diameter of the interior of the ring at this point. l

The lenses 2 and 3 fit within the retaining ring 4 and are slipped in-to the ring from the inner end thereof until they abut the shoulder `8. A clamping ring 9 screws into the inner end of theretaining ring 4 and clamps the lenses as' a unit against the shoulder 8, to hold the lenses securely andirmly in position. A

In order that the lenses 2 and 3 may notl be reversed and must always be placed in the ring 4 in correct position, I provide the interior of the retaining ring with inwardly extending projections or ribs 10, shownl as ex`- tending lengthwise of the ring 4. These projections or ribs may take various forms but are unequally spaced from each other as apparent from an inspection of Fig. 2. The lenses 2 and 3 are provided in their periphery with slots 11, spaced to correspond to -the spacing of the projections 10 on the ring 4, thereby preventing the lenses from being placed in the mount in other than the correct position, inasmuch as if the lenses were reversed the slots or grooves 11 in their peripheries would no longer register with the projections 10 on the ring and it would be impossible to insert the lenses into the retaining tube 4.

The rear element of this embodiment of my invention comprises the lenses 12 and 13 of a different diameter than the front element and hence not interchangeable therewith. 14 designatesa retaining tube threaded into the main tube 1. The' retaining tube is provided with an internal shoulder' 15. The lenses 12 fand 13 are not cemented to each other and have their peripheries notched as at 16, which notches are unequally spaced and cooperate with unequally spaced ribs projecting inlwardlywithin the retaining Itube 14. The numberv of notches and ribs, or their equivaf lent, for the len's 13 exceeds that for the lens 1 2 from which it will be evident reversal of these; two lenses is effectnally prevented. The lenses are held inV position in the ringv 14 by a clamping ring 18 which screws into the in- -ternally threaded end, of the retaining tube .14. This clamping ring is of such a length that if the lenses 12 and 13 are interchanged the ringcannot be screwed into its bearing. It will be seen from theforegoing that the front and rear elements of my lens system are non-interchangeable owing to their difmik ' l ference in diameter.. It is to be noted also' that by spacing the ribs and-slots 11 .of

the front element differently from the spac- `ing of the ribs and slots 17 and 18- of the rear element the two sets cannot be interchanged even though the lenses composing Ithe two elements were all of the same diameter.

- It will also be'evident that my construction prevents reversal of the lenses of each element.

In thev embodiment of my invention illustrated in Figs. 3 and 4,1 have varied the construction just described. The `front element composed of the Jtwo lenses '2 and 3 cemented together, `isclampedin a retaining tube 4 by a clamping ringl 5. The lenses2 `and 3 are provided with a tapered periphery -asfin'dicated at 19 while the interior of the tube 4- is correspondingly'tapered, and vinsertion of these lenses in reversed position is positively prevented.

The rear element composed of the separate4 lenses 12 and -13 are notonly'smaller in diameter than the front element and hence. noninterchangeable therewith, but are o different construction.

The retaining .ring 14 which screws into the tube 1 is tapered internally as indicated at 20, and'shoulderedat 15. Thelens 13 is correspondingly tapered and' hence can only be inserted correctly. The lens- 12 is provided with a clamping ring 21 spun aboutits periphery, the periphery of this fclamping i ring ein threaded as indicated at 21 so 'as ment is tapered internally. The lens13 7 is correspondingly tapered.` -The lens 12 'is tapered 'portion of said bore'to prevent re-l versal of said lens, a clam ing ring for the other lens', said ring being th ly to be received by th threaded portion of the bore of the retaini g tube to prevent in-` terchanging of the' two lenses and the exre'aded externalternal diameter of a portion of said ring be.S

ing. greater than that of the remaining portion of the ring to preventl reversal of the ring and its lens in said bore.

2. In'projector apparatus, 'a pair of separable lenses, a retaining tube therefor. having. a tapered bore for the rece tion of said lenses, the peripheryof one o said lenses being smooth and tapered to it said bore, the

periphery of the other lens being smooth and straight, a clamping ring spun over ,the periphery of the last mentioned lens, saidring being tapered externally and threaded into the tapered boreof said retaining tube. 3. I nprojector,l apparatus, the combination of a lens-tube, a retaining tube threaded into said lens'tube, said retaining' tube having itsl end adjacent the threaded portion enlarged to prevent reversal of the retainin tube in the lens tube, said retaining-'tube aving: a tapered bore, the outer portion of which bore iSthreaded, a lens having atapered periphery and adapted ,to it the inner Unthreaded portion of the tapered bore of the retaining tube,

a second lens cooperating withv the first lens,A

,a tapered clamping ring carried by said second lens, the periphery of the clamping ring being tapered and threaded to t the threaded tapered portion of the bore of the retaining tube.

This specification signed this 23rd day ofv January,l 1928. v KARL K RUENING.4

' provided with a rin 23 spun about the same.'

` I he retaining tube14 screws into an outer tube 24, and is enlarged at its end as lndi- This ring is tapere and is threaded on its' exterior'to screw into the retaining tube 14.`

v cated at 25 so that it cannot be reversed in the tube 24. Obviously thetwolenses 1'2" and 13'cannot,be reversed or interchanged.

.In all the. forms shown and described above, therefore, I have provided a construction `whereby'the frontv and rear nelements of the lens. system of'a projection gnachme can not j be interchanged and a' vconstruction wherein the lenses making up each element cannotbe reversed or interchanged.

tion of a pairof lenses, a retaining tube therefor, the bore WhatIclaimis-:' 1. In projector apparatus, the combinathrughout par of its length, the outer end f said tuba` being tapered of said -bore iieing themed, Vone of said Enseshaving its periphery'taperecl -to fit the ils ist4 

